Relevance of fermented food products in southwest Nigeria

Samples of extruded high protein weaning foods were produced using blends of peanuts, maize and soybean to achieve the desired level of protein. The extruded products, based on a raw and a preroasteds mix of ingredients, were developed and characterized in terms of the hot paste viscosity characteristics, chemical and nutritional quality, amino acid composition, and storage stability. A comparative evaluation of the extruded products was undertaken in relation to two similar existing products: the traditional roasted maize flour weaning food, and thecommercial version. In general, the extruded products were found to have better nutritional quality as indicated by the high protein content of 16.5–18.7% and quality, and excellent rat growth response. For both types of extruded weaning foods developed, between sixty- and one hundred-fold increases in mean weight gain of test rats were recorded over those eating the traditional sample. Correspondingly, the PER values which were between 2.3 and 2.5, were almost thrice the values obtained for the existing products. Significantly higher feed efficiency ratios were also obtained for the extruded products. Hematological data of test animals showed normal values for white blood cell (WBC) count, red blood cell (RBC) count, hemoglobin (Hb) levels and packed cell volume (PCV) for all the weaning foods studied, except the existing traditional roasted maize flour. In terms of storage stability of the extruded products, predicted shelf life periods of 7.8–10.4 months were obtained for the extruded raw blend, and 5.6–7.1 months for the extruded preroasted blend when stored at the average ambient temperature of about 30,°C in Ghana. In general, the preroasting treatment was found to reduce the quality characteristics of the extruded product.     

Alcohol production in submerged cashew pomace

The variations in the total titratable acidity, hydrogen ion concentration, reducing sugar, soluble solids and alcohol contents of the supernatant of the submerged cashew pomace in a non-aseptic condition were investigated. The crude fibre content of the pomace was also determined during fermentation. At intervals, the changes in microbial load in both the pomace and its supernatant were examined during the 14-day study. Fifty four percent of the total soluble solids (TSS) was utilised within 7 days of degradation while an increase of about 91% in the total titratable acidity occurred in the cashew pomace within the same period bringing its pH to 3.24. Acid hydrolysis of the pomace accounted for the relative high value of 2.15% TSS on the 8th day. Isolates of the generaLeuconostoc, Lactobacillus, Pediococcus, Aspergillus, Rhizopus and some yeast strains were obtained from the fresh pomace. The fungal colonies constituted about 76% of the population in the cashew pomace. The 86% drop in microbial population of the 8th day biodegraded pomace could be attributed to a decrease in nutrients of the substrate and the inhibitory effect of the organic acids produced during fermentation.     

Fermentation of yam: microbiology and sensory evaluation of cooked fermented yam tissues

The microflora of white yam ( Dioscorea rotundata L.) slices fermented anaerobically in 1.5 percent brine for five days at room temperature were studied. The hydrolysis of the carbohydrate and the subsequent conversion of sugars and minerals by the fermenting microbes contributed much to the increased microbial load especially within the first 72 hours of fermentation. The organisms implicated in the fermentation include the species of Pediococcus, Lactobacillus and Pseudomonas, Bacillus subtilis and two other Gram negative coccal cells, yet to be identified. The decrease in microbial counts at the latter stage of fermentation was attributed to the high total acidity of the medium, which was about 2.67 times the initial value of 0.027% lactic acid. Meanwhile, the lactic acid bacteria increased continuously throughout the period of fermentation.     

Potentials of biodegraded cashew pomace for cake baking

The use of biodegraded cashew pomace processed into flour for cake baking was investigated. The physico-chemical changes during the submerged fermentation of the pomace and the organoleptic qualities of the composite cake were also monitored. There was an increase of about 50% in protein content of the pomace after 96h of fermentation. However, a reduction of about 61% in the total microbial count after 24h was due to the toxic effect of the organic acids on the microbial cells during fermentation. The cashew flour had high crude fibre (ca. 20–33%) and carbohydrate (ca. 16–47%) values. The composite cake made from a 10:90 combination of 96h-degraded cashew flour/wheat flour respectively was the most accepted. The cake which had a specific volume of 0.53 ml/g lost 11.1% moisture when 38 g of its batter was exposed to 190°C for 10 minutes. This cake had a calorie value of 293.8/100 g and may be useful in feeding diabetic patients who require low carbohydrate foods.